Low molecular weight structured polymers

ABSTRACT

The present invention relates to novel low molecular weight, structured polymer compositions. The invention also relates to methods for inhibiting scale formation, precipitation or deposition; increasing dispersion of insoluble precipitates in process waters; treating cooling and boiler water; and reducing the viscosity of mineral slurries using the aforementioned polymer compositions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of application Ser. No. 08/926,665, filed Sep. 9,1997, now U.S. Pat. No. 6,096,847, which is a continuation ofapplication Ser. No. 08/577,524, filed Dec. 22, 1995, now abandoned.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to novel low molecular weight, structuredpolymer compositions. The invention also relates to methods forinhibiting scale formation, precipitation or deposition; increasingdispersion of insoluble precipitates in process waters; treating coolingand boiler water; and reducing the viscosity of mineral slurries usingthe aforementioned polymer compositions.

BACKGROUND OF THE INVENTION

Industrial and residential waters contain naturally occurringcontaminates (i.e., calcium, iron, barium, bicarbonate, carbonate,oxide, oxylate, sulfate, phosphate, zinc, etc.) that under conditions ofuse can chemically combine to form water insoluble precipitates.Additionally, water insoluble contaminates such as clay, silica and ironoxides can settle out of the water. These precipitates and inertmaterials can collect on surfaces of containers and piping in the formof deposits and scale, which reduce heat transfer, inhibit flow,increase likelihood of corrosion and enhance bacterial growth. In miningapplications, compositions which aid in fluidizing insolubleparticulates are desirable in order to more efficiently procure andtransport the mined materials.

Current mechanisms for controlling scale and deposits involve preventingformation of insoluble precipitates (e.g., limiting crystal growth) orkeeping inert insoluble materials dispersed in the system. Dispersantsfluidize precipitates, silts, solids and combinations thereof. Chelantsor sequestering agents can be used to bind cations to help prevent theformation of insoluble precipitates. Surface active agents can be usedto aid in the dispersion of inert clays and silica. By nature, some ofthese agents may also be useful in fluidizing high solids slurries ofores and minerals.

Certain low molecular weight organic polymers (less than 100,000 MW) arecapable of both inhibiting precipitation and keeping insolublecontaminates dispersed. These polymers are comprised of polycarboxylicand polysulfonic acids and their salts, copolymers of these acids, andco- and interpolymers of these acids with acrylamide, cationic monomers,vinyl esters and ethers.

In U.S. Pat. No. 3,463,730, Booth and Mead describe a process forcontrolling or preventing scale deposits in aqueous systems by additionof a low molecular weight (1,000-8,000) unhydrolyzed polyacrylamide.Booth and Cornelius, in U.S. Pat. No. 3,709,815 disclose polymerscontaining 2-acrylamido-2-substituted propane-1-sulfonic acid with anaverage molecular weight of at least 20,000 for use as boiler waterdispersives and conditioners. In U.S. Pat. No. 3,898,037, Lange et al.,describe polymers and co-polymers of acrylamido-sulfonic acid used indispersing water-insoluble compounds of iron, calcium, magnesium,aluminum and commonly occurring particles of silt and clay. Amick etal., in U.S. Pat. No. 4,711,725, disclose a variety of copolymers,terpolymers and interpolymers also utilzed for these applications. Ineach patent, the polymers described are linear in structure andcompletely water-soluble.

Low molecular weight organic polymers that are linear and water solublehave also been disclosed to fluidize or disperse minerals in highconcentration slurries. This allows more economical storage andtransport forms of the minerals. Amick et al., in U.S. Pat. No.4,711,725 demonstrates the abilities of co- and terpolymers ofcarboxylic and sulfonic acids to reduce the viscosity of clay andcalcium carbonate slurries. Again, these polymer compositions have alinear structure and are water soluble.

Structured, high molecular weight polymers have been previouslydisclosed. Ryles et al., in U.S. Pat. No. 5,171,808, disclosecross-linked, anionic or amphoteric, organic, polymeric microparticlesfor use in flocculating dispersions of suspended solids. In EuropeanPatent Application 0 374 458, Neff et al. disclose water-soluble,branched polymeric flocculants based on polymerization of ethlyenicallyunsaturated monomers and branching agents in the presence of achain-transfer agent. Both of these patents disclose compositions ofhigh molecular weight polymers used as flocculating agents, and used toinduce massing and precipitation of insoluble materials rather thandispersion of insoluble materials in a multiphase system.

While the aforementioned compositions utilized as scale inhibitors anddispersants may be applicable under specific conditions, they are onlymoderately effective or ineffective under certain circumstances.Therefore, a need exists for alternative compositions and methods forinhibiting scale formation, precipitation or deposition; increasingdispersion of insoluble precipitates in process waters; treating coolingand boiling water; and reducing the viscosity of mineral slurries.

SUMMARY OF THE INVENTION

This invention provides novel low molecular weight structured polymercompositions comprising ethylenically unsaturated monomers andstructure-inducing agents. These structured polymers possess molecularstructure that is branched, cross-linked or some combination thereof, asopposed to polymers that possess linear molecular structure. Thestructured polymers of this invention have improved capability forinhibiting the formation, precipitation or deposition of scale, improvedcapability of dispersing insoluble precipitates in aqueous systems,improved capability in treating cooling and boiler water, and improvedcapability to reduce the viscosity of mineral slurries compared toexisting polymers.

It is a principal object of this invention to provide polymercompositions having a molecular weight of less than about 500,000comprising at least one unsaturated organic monomer or salts thereof,and at least one structure-inducing agent.

Other objects of this invention are to provide: methods for inhibitingscale formation, precipitation or deposition in an aqueous mediumcomprising the step of adding to said aqueous medium an effective amountof a polymer composition comprising at least one unsaturated organicmonomer and at least one structure-inducing agent; methods forincreasing dispersion of insoluble precipitates in process waterscomprising the step of adding to said process waters an effective amountof a polymer composition comprising at least one unsaturated organicmonomer and at least one structure-inducing agent; methods of treatingcooling and boiler water comprising the step of adding to said coolingand boiler water an effective amount of a polymer composition comprisingat least one unsaturated organic monomer and at least onestructure-inducing agent; and methods of reducing the viscosity of amineral slurry comprising the step of adding to said slurry an effectiveamount of the polymer composition comprising at least one unsaturatedorganic monomer and at least one structure-inducing agent.

DETAILED DESCRIPTION OF THE INVENTION

In order that the invention herein described may be more fullyunderstood, the following detailed description is set forth. In thedescription, the following abbreviations are used:

Designation Reagent or Fragment AA acrylic acid AM acrylamide AMPS2-acrylamido-2-methylpropane sulfonic acid COM. commercial DADMACdiallyldimethylammonium chloride EDTA ethylenediaminetetraacetic acidGPC gel permeation chromatography MA methyl acrylate MAn maleicanhydride MBA methylenebisacrylamide MBS sodium metabisulfite ME2-mercaptoethanol NVP N-vinylpyrrolidone PAA polyacrylic acid SAHSsodium allyloxy-2-hydroxypropylsulfonate T-BAM t-butylacrylamide

The following terms are employed herein:

The term “branching” refers to the creation of branches or additionaltermini relative to the two original termini that exist in linearentities.

The term “branching agent” refers to an agent which causes branching tooccur.

The term “cross-link” refers to an interconnection between polymerchains.

The term “cross-linking agent” refers to an agent which inducescross-linking, branching or a combination thereof to occur.

The term “ethylenically unsaturated” refers to the presence of at leastone unsaturated ethylenic group.

The term “interpolymer” refers to a polymer formed from three or moredifferent monomers.

The term “monomer” refers to single, discreet molecule which is capableof combining to form polymers.

The term “structured polymer” refers to a polymer prepared withincorporation of a structure-inducing agent.

The term “structure-inducing agent” refers to an agent which, when addedto a polymer composition, induces branching, cross-linking or acombination thereof.

In view of the above definitions, other terms of chemical and polymertechnology used throughout this application can be easily understood bythose of skill in the art. Terms may be used alone or in any combinationthereof.

This invention provides a polymer composition having a molecular weightof less than about 500,000 comprising at least one unsaturated organicmonomer or salts thereof, and at least one structure-inducing agent.

In a preferred embodiment of this invention, each unsaturated organicmonomer is independently selected from the group consisting ofmonoethylenically unsaturated carboxylic acids, monoethylenicallyunsaturated carboxylic acid anhydrides, monoethylenically unsaturatedsulfonic acids, and sulfonated styrene. More preferably, eachunsaturated organic monomer is independently selected from the groupconsisting of acrylic acid, methacrylic acid, maleic acid, maleicanhydride, 2-acrylamido-2-methylpropane sulfonic acid,2-methacrylamido-2-methylpropane sulfonic acid, andallyloxy-2-hydroxypropyl sulfonic acid.

In another preferred embodiment of this invention, thestructure-inducing agent is a crosslinking or branching agent. Morepreferably, the structure-inducing agent is independently selected fromthe group consisting of polyunsaturated acrylic amides, polyunsaturatedacrylic esters, alkenyl-substituted heterocycles, tri- or tetra-allylicquaternary ammonium halides, and aldehydes. Even more preferably, thestructure-inducing agent is independently selected from the groupconsisting of methylenebisacrylamide, triallylmethylammonium chloride,ethylene glycol diacrylate, glyoxal and formaldehyde.

In a further embodiment, this invention provides a polymer compositionhaving a molecular weight of less than about 500,000 comprising acopolymer of unsaturated organic monomers and a structure-inducingagent.

In a preferred embodiment of this invention, the copolymer comprisesunsaturated organic monomers independently selected from the groupconsisting of monoethylenically unsaturated carboxylic acids,monoethylenically unsaturated carboxylic acid anhydrides,monoethylenically unsaturated sulfonic acids and sulfonated styrene.More preferably, the copolymer comprises unsaturated organic monomersindependently selected from the group consisting of acrylic acid,methacrylic acid, maleic acid, maleic anhydride,2-acrylamido-2-methylpropane sulfonic acid,2-methacrylamido-2-methylpropane sulfonic acid andallyloxy-2-hydroxypropyl sulfonic acid.

In another embodiment, the copolymer comprises one unsaturated organicmonomer independently selected from the group consisting ofmonoethylenically unsaturated carboxylic acids, monoethylenicallyunsaturated carboxylic acid anhydrides, monoethylenically unsaturatedsulfonic acids and sulfonated styrene; and one unsaturated organicmonomer selected from the group consisting of unsaturated acrylicamides, unsaturated acrylic esters, alkenyl-substituted heterocycles andunsaturated quaternary ammonium halides. More preferably, the copolymercomprises an unsaturated organic monomer selected from the groupconsisting of acrylic acid, methacrylic acid, maleic acid, maleicanhydride, 2-acrylamido-2-methylpropane sulfonic acid,2-methacrylamido-2-methylpropane sulfonic acid, allyloxy-2-hydroxypropylsulfonic acid and sulfonated styrene; and an unsaturated organic monomerselected from the group consisting of acrylamide, substitutedacrylamides, N-vinylpyrrolidone, methacrylate, ethylacrylate, anddiallylic quaternary ammonium halides.

In another embodiment, this invention provides a polymer compositionhaving a molecular weight of less than about 500,000 comprising aninterpolymer of unsaturated organic monomers and a structure-inducingagent.

In a preferred embodiment, the interpolymer comprises at least oneunsaturated organic monomer independently selected from the groupconsisting of monoethylenically unsaturated carboxylic acids,monoethylenically unsaturated carboxylic acid anhydrides,monoethylenically unsaturated sulfonic acids and sulfonated styrene; andadditional unsaturated organic monomers independently selected from thegroup consisting of monoethylenically unsaturated carboxylic acids,monoethylenically unsaturated carboxylic acid anhydrides,monoethylenically unsaturated sulfonic acids, sulfonated styrene,unsaturated acrylic amides, unsaturated acrylic esters,alkenyl-substituted heterocycles and unsaturated quaternary ammoniumhalides.

More preferably, at least one unsaturated organic monomer isindependently selected from the group consisting of acrylic acid,methacrylic acid, maleic acid, maleic anhydride,2-acrylamido-2-methylpropane sulfonic acid,2-methacrylamido-2-methylpropane sulfonic acid, allyloxy-2-hydroxypropylsulfonic acid and sulfonated styrene; and additional unsaturated organicmonomers are independently selected from the group consisting of acrylicacid, methacrylic acid, maleic acid, maleic anhydride,2-acrylamido-2-methylpropane sulfonic acid,2-methacrylamido-2-methylpropane sulfonic acid, allyloxy-2-hydroxypropylsulfonic acid, acrylamide, substituted acrylamides, N-vinylpyrrolidone,methacrylate, ethylacrylate, and diallylic quaternary ammonium halides.

In an alternate embodiment, this invention provides a polymercomposition having a molecular weight of less than about 500,000comprising at least one unsaturated organic monomer or salts thereof,and at least one structure-inducing agent, wherein unsaturated organicmonomers independently selected from the group consisting ofmonoethylenically unsaturated carboxylic acids, monoethylenicallyunsaturated carboxylic acid anhydrides, monoethylenically unsaturatedsulfonic acids and sulfonated styrene comprise between about 50% andabout 100% of the total composition and more preferably between about70% and about 100% of the total composition.

In a further embodiment, this invention provides a polymer compositionhaving a molecular weight of less than about 500,000 comprising at leastone unsaturated organic monomer or salts thereof, and at least onestructure-inducing agent, wherein the molecular weight of the polymer isless than 100,000 amu, and more preferably less than 50,000 amu.

In another embodiment, this invention provides a polymer compositionhaving a molecular weight of less than about 500,000 comprising at leastone unsaturated organic monomer or salts thereof, and at least onestructure-inducing agent, wherein the concentration ofstructure-inducing agent is between about 50 and about 20,000 ppm.

In an alternate embodiment, this invention provides methods forinhibiting scale formation, precipitation or deposition in an aqueousmedium; for increasing dispersion of insoluble precipitates in processwaters; and for treating cooling and boiler water; comprising the stepof adding to said aqueous medium, process waters and cooling and boilerwater an effective amount of a polymer composition having a molecularweight of less than about 500,000 comprising at least one unsaturatedorganic monomer and at least one structure-inducing agent.

In another embodiment, this invention provides a method of reducing theviscosity of a mineral slurry comprising the step of adding to saidslurry an effective amount of the polymer composition having a molecularweight of less than about 500,000 comprising at least one unsaturatedorganic monomer and at least one structure-inducing agent. In apreferred embodiment, the mineral slurry comprises one or more mineralsselected from the group consisting of calcium carbonate, titaniumdioxide, coal, calcined kaolin clay and hydrated kaolin clay. In analternate preferred embodiment the mineral slurry comprises at least onemetal, preferably a transition metal.

In alternate preferred embodiments, this invention includes the methodsdescribed above wherein the polymer composition comprises the preferred,more preferred and even more preferred polymer compositions describedabove.

The structured polymers described herein can be prepared by conventionalpolymerization techniques well-known to those skilled in the art. Suchtechniques include, but are not limited to, solution polymerization,reverse-phase emulsion polymerization and suspension polymerization.Polymerization may be initiated via a free radical initiator. Thepreferred initiator method is free radical, however, photochemical orradiation methods may also be utilized. The introduction of thestructure-inducing agent may be performed either prior to, concurrentwith or after combining the other agents necessary for formation of thestructured polymers of this invention.

Where carboxylic acids, or their salts thereof, are used for thepreparation of compositions of this invention, it is also envisionedthat esters, amides or nitrites may be hydrolyzed to give the desiredcarboxylic acid. This hydrolysis may occur before or after apolymerization event.

In order to obtain the low molecular weight polymers of this invention,it is necessary to use a chain transfer agent in their preparation.Examples of chain transfer agents which may be used are well-known tothose skilled in the art. They include, but are not limited to, agentssuch as alcohols, phosphites, phosphinic acids, sulfites, mercaptans,and thioacids. The amount of chain transfer agent necessary will beinfluenced by factors such as efficiency of the compound, the monomermixture used, the amount of structure-inducing agent present and thedesired molecular weight of the final product. A combination of two ormore chain transfer agents may be used in one formulation.

In order that this invention be more fully understood, the followingexamples are set forth. These examples are for the purposes ofillustration and are not to be construed as limiting the scope of theinvention in any way.

EXAMPLES Example 1

Copolymers containing 40 weight % AMPS/60 weight % AA and 20 weight %AMPS/80 weight % AA, neutralized to pH 3.5-6.0 with sodium hydroxide,were prepared via aqueous solution polymerization. Ammonium persulfateand sodium metabisulfite were used as the initiator/chain transfersystem. The formulations contained 0-5000 ppm MBA as the structureinducing agent. The final products were between 30% and 40% active asacid. Specific data, including molecular weight as determined by GPC,are detailed in Table 1.

TABLE 1 SAMPLE COMPOSITION PPM MBA MW 1A 40/60 AMPS/AA 0 25,900 1B 40/60AMPS/AA 100 18,100 1C 20/80 AMPS/AA 0 14,100 1D 20/80 AMPS/AA 500087,100 1E 20/80 AMPS/AA 0 19,300 1F 20/80 AMPS/AA 1000 18,200 1G 20/80AMPS/AA 0  7,400 1H 20/80 AMPS/AA 1000  4,940 1I 20/80 AMPS/AA 5000 6,400

Example 2

Homopolymers of polyacrylic acid were prepared by the same methoddescribed in Example 1 without neutralization. Polymer formulationscontained from 0-20,000 ppm MBA as the structure inducing agent. In somecases 2-mercaptoethanol (ME) was used in conjunction with sodiummetabisulfite (MBS) as the chain transfer system. Specific data aregiven in Table 2.

TABLE 2 MOLECULAR SAMPLE CHAIN TRANSFER PPM MBA WEIGHT 2A MBS 500 2B MBS1,000 57,000 2C MBS 1,000 65,600 2D MBS/2ME 1,250  7,400 2E MBS/2ME2,500  8,800 2F MBS/2ME 5,000 11,000 2G MBS/2ME 5,000 — 2H MBS/2ME10,000 — 2I MBS/2ME 15,000 — 2J MBS/2ME 20,000 — 2K MBS/2ME 15,000 — 2LMBS/2ME 5,000 — 2M MBS/2ME 5,000 —

Example 3

A series of homo-, co- and terpolymers were prepared with othercarboxylic acids, sulfonic acids and several co- and terpolymers wereprepared incorporating cationic and nonionic molecules in the polymercomposition. All polymers were prepared according to Example 1 andadding 0 to 5000 ppm MBA as the structure inducing agent. Specific dataare given in Table 3. All polymers shown in Table 3 were prepared toachieve a desired molecular weight below 15,000.

TABLE 3 SAMPLE COMPOSITION PPM MBA 3A 60/20/20 AA/AMPS/DADMAC 0 3B60/20/20 AA/AMPS/DADMAC 5000 3C 70/20/10 AA/AMPS/NVP 0 3D 70/20/10AA/AMPS/NVP 5000 3E 80/20 AA/SAHS 0 3F 80/20 AA/SAHS 5000 3G 70/20/10AA/AMPS/AM 0 3H 70/20/10 AA/AMPS/AM 5000 3I 80/20 AA/AM 0 3J 80/20 AA/AM5000 3K 70/20/10 AA/AMPS/MA 0 3L 70/20/10 AA/AMPS/MA 5000 3M 80/20 AA/MA0 3N 80/20 AA/MA 5000 3O HOMOPOLYMER AMPS 0 3P HOMOPOLYMER AMPS 5000 3Q70/20/10 AA/AMPS/TBAM 0 3R 70/20/10 AA/AMPS/TBAM 5000 3S HOMOPOLYMER MAn0 3T HOMOPOLYMER MAn 5000

Examples 4-13

All of the samples described in Examples 1-3 were tested for performancein a variety of applications. The samples described in Examples 1-3 alsowere tested against commercially available materials that are presentlyused for these applications. Molecular weights were measured on thecommercial products by GPC using the same method as was used for thelaboratory samples described in the examples. As different methods ofanalysis can produce a variation in the result, molecular weights on allmaterials were measured by the same procedure. Data on these commercialproducts is detailed in Table 4.

TABLE 4 SAMPLE COMPOSITION MW 4A COM. AA/AMPS 28,700  4B COM. AA/AMPS8,100 4C COM. PAA 3,730 4D POLYACRYLATE (COM) 5,400 4E POLYACRYLATE(COM) 3,900 4F POLYACRYLATE (COM) 4,500

Example 4 Calcium Carbonate Inhibition

SET 1 - 70° C., 1 PPM POLYMER DOSAGE SAMPLE POLYMER PPM MBA MW %INHIBITION 1A 60/40 AA/AMPS 0 25,900 36.7 1B 60/40 AA/AMPS 100 18,10042.2 1C 80/20 AA/AMPS 0 14,100 40.4 1D 80/20 AA/AMPS 5000 87,100 48.6 4C100% AA (COM) 0  3,730 9.2 2C 100% AA 1000 65,600 46.8 SET 2 - 70° C., 1PPM POLYMER DOSAGE 4C 100% AA (COM) 0  3,730 39.8 2A 100% AA 500 — 52.72F 100% AA 5000 11,000 52.7 SET 3 - 70° C. PPM SAMPLE POLYMER MBA MWDOSE % INHIBITION 1G 80/20 AA/AMPS 0 7400 1 PPM 35.9 1I 80/20 AA/AMPS5000 6400 1 PPM 56.8 1G 80/20 AA/AMPS 0 7400 4 PPM 63.0 1I 80/20 AA/AMPS5000 6400 4 PPM 80.7 4B COM. AA/AMPS 0 8100 4 PPM 64.9 SET 4 - 80° C.,2.5 PPM POLYMER DOSAGE SAMPLE POLYMER PPM MBA MW % INHIBITION 1G 80/20AA/AMPS 0 7,400 44.9 1I 80/20 AA/AMPS 5000 6,400 57.6 4B COM. AA/AMPS 08,100 29.7 SET 5 - 70° C., 1 PPM POLYMER DOSAGE PPM SAMPLE POLYMER MBA %INHIBITION 1G 80/20 AA/AMPS 0 61.1 1I 80/20 AA/AMPS 5000 77.9 4B COM.AA/AMPS 0 58.9 3A 60/20/20 AA/AMPS/DADMAC 0 53.3 3B 60/20/20AA/AMPS/DADMAC 5000 62.2 3C 70/20/10 AA/AMPS/NVP 0 61.1 3D 70/20/10AA/AMPS/NVP 5000 68.9 1G 80/20 AA/AMPS 0 47.4 1I 80/20 AA/AMPS 5000 61.94B COM. AA/AMPS 0 43.3 3E 80/20 AA/SAHS 0 34.0 3F 80/20 AA/SAHS 500045.4 3G 70/20/10 AA/AMPS/AM 0 42.3 3H 70/20/10 AA/AMPS/AM 5000 55.7 3I80/20 AA/AM 0 26.8 3J 80/20 AA/AM 5000 35.1 3K 70/20/10 AA/AMPS/MA 032.0 3L 80/20/10 AA/AMPS/MA 5000 41.2 3M 80/20 AA/MA 0 24.7 3N 80/20AA/MA 5000 33.0 3O 100% AMPS 0 18.6 3P 100% AMPS 5000 25.8 3Q 70/20/10AA/AMPS/TBAM 0 39.1 3R 70/20/10 AA/AMPS/TBAM 5000 47.8 3S HOMOPOLYMERMAn 0 22.8 3T HOMOPOLYMER MAn 5000 31.5

Calcium Carbonate Inhibition Test Procedure

All tests for calcium carbonate inhibition were conducted according tothe following procedure:

1. Add 50 ml 0.023M calcium stock solution (prepared from CaCl₂ andneutralized to pH 8.5) to glass vessel.

2. Add 0 (control), 0.1, 0.25 or 0.5 ml of 1g/l active polymer solution(neutralized to pH 8) 1, 2.5 and 5 ppm respectively, to vessel.

3. Add 50 ml 0.023M carbonate stock solution (prepared from Na₂CO₃ andneutralized to pH 8.5) to vessel.

4. Cap vessel and shake to mix.

5. Place jars in forced air oven set at required temperature (70 or 80°C.) for 17 hrs. After approximately 60 minutes, loosen cap and recap torelease pressure.

6. After 17 hrs., remove from oven and let cool to room temperature.

7. Filter through 0.45 micron filter.

8. Add 25 ml of filtered solution to beaker with 25 ml of water.

9. Add 3 ml of water hardness buffer solution and calcium indicator.

10. Titrate with 0.01M EDTA solution.

11. % Inhibition=ml EDTA (sample)−ml EDTA (control)×100 ml EDTA(titration control)−ml EDTA (control)

where titration control=50 ml calcium stock solution+50 ml waterprepared fresh prior to titration; EDTA (control)=0 ppm polymer

Example 5 Calcium Phosphate Inhibition

10 PPM POLYMER, pH 9.5, 70° C. SAMPLE POLYMER PPM MBA MW % INHIBITION 1G80/20 AA/AMPS   0 7,400 81.0 1H 80/20 AA/AMPS 1000 4,940 90.1 1I 80/20AA/AMPS 5000 6,400 95.0 1D 80/20 AA/AMPS 5000 87,100  94.6 4B COM.AA/AMPS   0 8,100 81.3

Calcium Phosphate Inhibition Test Procedure

All tests for calcium phosphate inhibition were conducted according tothe following procedure:

1. Add 50 ml of 12 ppm PO₄ stock solution to glass vessel.

2. Add desired polymer dose (1, 5, or 10 ppm) to vessel.

3. Add 50 ml 500 ppm calcium stock solution containing 5 ppm Fe⁺².

4. Adjust samples to desired pH (9.5)

5. Cap and place in 70° C. forced air oven for 17 hrs.

6. After approximately 60 minutes, release pressure in vessels.

7. Remove from oven and filter immediately through 0.22 micron filter.

8. Analyze for PO₄ by ascorbic acid method.

9. % Inhibition=%Phosphate sample−%Phosphate Control×100%PhosphateTitration Control−%Phosphate Control

Example 6 Calcium Sulfate Inhibition ph 8.5, 70° C., 72 hrs

SAM- PPM % PLE POLYMER MBA MW DOSE INHIBITION 4C 100% AA (COM) 0 3730 .1PPM 0 2G 100% AA 5000 11,000   .1 PPM 8.2 2A 100% AA 500 — .1 PPM 8.2 4BCOM. AA/AMPS 0 8100 .1 PPM 5.5 1I 80/20 AA/AMPS 5000 6400 .1 PPM 10.9 4BCOM. AA/AMPS 0 8100 .5 PPM 24.7 1G 80/20 AA/AMPS 0 7400 .5 PPM 28.7 1I80/20 AA/AMPS 5000 6400 .5 PPM 35.6

Calcium Sulfate Test Procedure

All tests for calcium sulfate inhibition were conducted according to thefollowing procedure:

1. Add 50 ml 15.3 g/l solution of calcium chloride (pH 8.5) to glassvessel.

2. Add desired polymer dose (0.1 or 0.5 ppm) to vessel.

3. Add 50 ml 8.1 g/l sodium sulfate solution (pH 8.5) to vessel.

4. Place in 70° C. forced air oven for 72 hrs. Release pressure after 1hr.

5. Cool to room temperature

6. Filter through 0.22 micron filter

7. Titrate for calcium with EDTA.

8. % Inhibition=ml EDTA (sample)−ml EDTA (control)×100 ml EDTA(titration control)−ml EDTA (control)

where titration control=50 ml calcium stock solution+50 ml waterprepared fresh prior to titration; EDTA (control)=0 ppm polymer

Example 7 Iron Oxide Dispersion

SET 1 SAMPLE POLYMER DOSAGE PPM MBA % T 1 hr % T 2 hr % T 3 hr CONTROLNONE 0 43.7 54.2 67.0 1E 80/20AA/AMPS 10 PPM 0 41.4 43.8 49.2 1F80/20AA/AMPS 10 PPM 1000 34.3 36.9 40.2 SET 2 SAMPLE POLYMER DOSAGE PPMMBA % T 1 hr CONTROL NONE 0 59.4 1C 80/20 AA/AMPS 0 0 38.1 1D 80/20AA/AMPS 1 PPM 5000 34.3 4A COM. AA/AMPS 1 PPM 0 42.4 SET 3 CONTROL NONE0 59.4 4C COM. AA 10 PPM 0 52.0 2B AA 10 PPM 1000 43.4 2C AA 10 PPM 100046.8

Iron Oxide Inhibition Test Procedure

All tests for iron oxide inhibition were conducted according to thefollowing procedure:

1. Prepare 200 ppm suspension of iron oxide in the presence of 250 ppmcalcium.

2. Mix for 30 minutes.

3. Place 100 ml aliquots into glass vessels.

4. Add polymer at desired concentration.

5. Agitate samples for 15 minutes.

6. Let stand for desired time period.

7. Pipet 10 ml aliquot from top and measure % transmittance with aspectrophotometer at 720 nm.

8. The lower the % transmittance, the greater dispersion capability.

Example 8

SAMPLE POLYMER DOSAGE PPM MBA % T 2.5 hr CONTROL NONE 0 39.8 4C COM. AA10 PPM 0 35.4 2C AA 10 PPM 1000 31.5 1C 80/20AA/AMPS 10 PPM 0 10.3 1D80/20AA/AMPS 10 PPM 5000 6.8 1F 80/20AA/AMPS 10 PPM 1000 7.7

Clay Dispersion Procedure

All tests for clay dispersion were conducted as in the iron oxide testprocedure except that a 1000 ppm clay suspension was prepared in thepresence of 250 ppm calcium.

Examples 4-8 demonstrate that the polymer compositions of this inventionpossess enhanced capability to inhibit scale formation, precipitation ordeposition, and provide increased dispersion of insoluble particulatesin process waters.

Example 9 Calcium Carbonate Viscosity Reduction—70% Slurry

Two structured sodium polyacrylate polymers were evaluated against acommercially available dispersant commonly used in this application,according to the following procedure:

1. Add the following to a 400 ml beaker:

a. 100 ml water,

b. 4.5 ml 10% active polymer solution, and

c. Add 250 g calcium carbonate slowly while mixing.

2. After all calcium carbonate is added, mix at high speed for 15minutes.

3. Pour into an 8 oz jar.

4. Measure viscosity with Brookfield viscometer, Model RVF, at 20 rpm.

5. Add additional polymer in 4.5 ml increments, upon each additionrepeat step 2 for 5 minutes then repeat step 4.

SAMPLE PPM MBA MW DOSAGE VISCOSITY (CPS) 4C 0  3,730 4.5 ml — 9.0 ml48,740  13.5 ml 6,620 18.0 ml 5,790 22.5 ml 5,950 2D 1250  7,400 4.5 ml— 9.0 ml 35,960  13.5 ml 2,980 18.0 ml 3,560 2F 5000 11,000 4.5 ml — 9.0ml 42,350  13.5 ml 3,750 18.0 ml 4,230

Example 10 Kaolin Clay Viscosity Reduction—70% Slurry

A series of 80/20 AA/AMPS copolymers were evaluated as dispersants for a70% slurry of kaolin clay. The test procedure used was identical to theprocedure of Example 9 except that, 10% active polymer and 10% activesodium carbonate were added in 10 ml increments. Performance wasmeasured with a Brookfield viscometer, Model RVF, at 20 rpm.

SAMPLE PPM MBA MW DOSAGE VISCOSITY (CPS) 1E 0 19,300 1.5 ml 1265  2.0 ml860 2.5 ml 865 1F 1000 18,200 1.5 ml 925 2.0 ml 750 2.5 ml 740

Example 11 Kaolin Clay Viscosity Reduction—70% Slurry

DOSAGE VISCOSITY (CPS) VISCOSITY (DN−cm × 10⁵) SAMPLE PPM MBA MW(LB/TON) BROOKFIELD HERCULES Measured at 1100 rpm 4F 0 4,500 3.25 8303.50 484 3.75 283 4.00 270 7.2 2D 1,250 7,400 2.75 768 3.00 350 3.25 2973.50 340 4.8 2F 5,000 11,000 2.75 430 3.00 470 5.9 Measured at 4400 rpm4F 0 4,500 3.00 752 3.25 163 42.0 2K 15,000 — 3.00 1057 3.25 255 28.0

The above tests were conducted using hydrated mid-Georgia kaolin clay.

Example 12 Kaolin Clay Viscosity Reduction—70% Slurry

DOSAGE VISCOSITY (CPS) VISCOSITY (DN−cm× 10⁵) SAMPLE PPM MBA MW (LB/TON)BROOKFIELD HERCULES Measured at 4400 rpm 4F   0 4,500 2.5 250 3.8 2D1250  7400 2.5 320 2.7 2L 5000 — 3.0 250 2.8 2M 5000 — 3.0 360 3.2

The above example was conducted using Eastern Georgia clay, whichgenerally is finer in particle size than mid-Georgia kaolin clay.

Example 13 Calcined Kaolin Viscosity Reduction—50% Slurry

MAX. RPM VISCOSITY ACHIEVED PPM DOSAGE HERCULES at 16 SAMPLE MBA MWLB./TON (Cps) dyne−cm × 10⁵ 4F 0 4500 2.0 784 780 2.5 779 785 2D 12507400 2.0 679 900 2.5 611 1000 2K 15,000 2.0 799 765 2.5 593 1030

The Hercules viscosity data shown in Example 13 give both a Herculesviscosity number in dynes and an rpm reading. The procedures forevaluating both hydrated and calcined kaolin slurries are given below:

The 70% hydrated kaolin slurry used in Examples 11-13 were prepared asfollows:

1. Prepare solutions of 10% active polymer and 10% active sodiumcarbonate.

2. Weigh out 500 g clay.

3. Weigh 200 g water into vessel for high speed mixer.

4. Add 2 pounds/ton active sodium carbonate.

5. Add 2 pounds/ton active polymer.

6. Mix until homogeneous and then add clay to vessel while mixing at ashigh a speed as possible.

7. If mixture is not fluid, add additional polymer and sodium carbonateat equal concentrations. Mix for 1 minute at high speed.

8. After all clay is added check pH of slurry (should be between6.5-7.5).

9. Check % solids (should be approximately 70.2%)

10. Check Brookfield viscosity with Model RVF spindle 1 or 2 at 20 rpm.

11. Record viscosity—Add additional 0.25 pounds/ton until optimum isreached (add 0.25 pounds/ton of sodium carbonate along with polymer).

12. Take Hercules viscosity on final sample at either 1100 or 4400 rpm,using B Bob.

The 50% calcined kaolin slurry used in Example 14 was prepared asfollows:

1. Weigh out 300 g calcined kaolin.

2. Weigh 288.5 g water into vessel for low sheer mixer.

3. Add 1.5 g each of 10% active dispersant solution and 10% activesodium carbonate solution.

4. Mix until homogeneous.

5. Add clay to water mixture slowly.

6. After all clay is added, mix at high speed for 1 minute.

7. Measure pH and % solids (pH should be 6.5-7.5 and % solids should beapproximately 50%).

8. Take Hercules viscosity at 1100 rpm, using B Bob.

Examples 9-13, described above, demonstrate that the polymercompositions of this invention possess enhanced capability to reduce theviscosity of mineral slurries compared to existing technology.

While described herein are a number of embodiments of this invention, itis apparent that the basic constructions may be altered to provide otherembodiments which utilize the products of this invention. Therefore, itwill be appreciated that the scope of this invention is to be defined bythe appended claims, rather than by the specific embodiments which havebeen presented by way of example.

I claim:
 1. A method for inhibiting scale formation, precipitation ordeposition in an aqueous medium comprising the step of adding to saidaqueous medium an effective amount of a dispersant polymer compositionhaving a molecular weight of less than about 50,000 comprising: at leastone unsaturated organic monomer or salts thereof, wherein theunsaturated organic monomer is independently selected from the groupconsisting of monoethylenically unsaturated carboxylic acids,monoethylenically unsaturated carboxylic acid anhydrides,monoethylenically unsaturated sulfonic acids and sulfonated styrene; andat least one structure-inducing agent.
 2. The method according to claim1, wherein the dispersant polymer composition comprises a copolymer ofunsaturated organic monomers.
 3. The method according to claim 2,wherein the copolymer comprises unsaturated organic monomersindependently selected from the group consisting of acrylic acid,methacrylic acid, maleic acid, maleic anhydride,2-acrylamido-2-methylpropane sulfonic acid,2-methacrylamido-2-methylpropane sulfonic acid andallyloxy-2-hydroxypropyl sulfonic acid.
 4. The method according to claim2, wherein the copolymer comprises one unsaturated organic monomerselected from the group consisting of monoethylenically unsaturatedcarboxylic acids, monoethylenically unsaturated carboxylic acidanhydrides, monoethylenically unsaturated sulfonic acids and sulfonatedstyrene; and one unsaturated organic monomer selected from the groupconsisting of unsaturated acrylic amides, unsaturated acrylic esters,alkenyl-substituted heterocycles and unsaturated quaternary ammoniumhalides.
 5. The method according to claim 4, wherein the copolymercomprises an unsaturated organic monomer selected from the groupconsisting of acrylic acid, methacrylic acid, maleic acid, maleicanhydride, 2-acrylamido-2-methylpropane sulfonic acid,2-methacrylamido-2-methylpropane sulfonic acid, andallyloxy-2-hydroxypropyl sulfonic acid; and an unsaturated organicmonomer selected from the group consisting of acrylamide, substitutedacrylamides, N-vinylpyrrolidone, methylacrylate, ethylacrylate, anddiallylic quaternary ammonium halides.
 6. The method according to claim1, wherein the dispersant polymer composition comprises an interpolymerof unsaturated organic monomers.
 7. The method according to claim 6,wherein the interpolymer comprises at least one additional unsaturatedorganic monomer independently selected from the group consisting ofmonoethylenically unsaturated carboxylic acids, monoethylenicallyunsaturated carboxylic acid anhydrides, monoethylenically unsaturatedsulfonic acids, sulfonated styrene, unsaturated acrylic amides,unsaturated acrylic esters, alkenyl-substituted heterocycles andunsaturated quaternary ammonium halides.
 8. The method according toclaim 7, wherein at least one unsaturated organic monomer isindependently selected from the group consisting of acrylic acid,methacrylic acid, maleic acid, maleic anhydride,2-acrylamido-2-methylpropane sulfonic acid,2-methacrylamido-2-methylpropane sulfonic acid andallyloxy-2-hydroxypropyl sulfonic acid; and additional unsaturatedorganic monomers are independently selected from the group consisting ofacrylic acid, methacrylic acid, maleic acid, maleic anhydride,2-acrylamido-2-methylpropane sulfonic acid,2-methacrylamido-2-methylpropane sulfonic acid, allyloxy-2-hydroxypropylsulfonic acid, acrylamide, substituted acrylamides, N-vinylpyrrolidone,methylacrylate, ethylacrylate, and diallylic quaternary ammoniumhalides.
 9. The method according to claim 1, wherein thestructure-inducing agent is independently selected from the groupconsisting of polyunsaturated acrylic amides, polyunsaturated acrylicesters, alkenyl-substituted heterocycles, tri- or tetra-allylicquaternary ammonium halides, and aldehydes.
 10. The method according toclaim 9, wherein the structure-inducing agent is independently selectedfrom the group consisting of methylenebisacrylamide,triallylmethylammonium chloride, ethylene glycol diacrylate, glyoxal andformaldehyde.